Conventionally, a plurality of technologies related to a solid-state imaging device which receives visible light and near infrared light have been disclosed. In such a solid-state imaging device, it is possible to acquire a normal image obtained by visible light (hereinafter referred to as “visible light image”), and an image containing information on a distance to an object and the like, which is obtained by near infrared light (hereinafter referred to as “near infrared light image”), using one solid-state imaging device.
For example, Japanese Unexamined Patent Application, First Publication No. 2010-081609 discloses a solid-state imaging device in which each of a normal pixel receiving visible light (hereinafter referred to as “visible light detection pixel”, and a pixel for near infrared light receiving near infrared light (hereinafter referred to as “near infrared light detection pixel”) is disposed on the same surface in a pixel region. More specifically, in the solid-state imaging device disclosed in Japanese Unexamined Patent Application, First Publication No. 2010-081609, a set of four visible light detection pixels of red (R), green (G), blue (B), and green (G) vertically and horizontally adjacent to each other, which are handled as one set in a general solid-state imaging device that does not receive near infrared light, and a pixel for near infrared light are arranged in a zigzag pattern at positions that do not overlap each other in a pixel region. To the solid-state imaging device disclosed in Japanese Unexamined Patent Application, First Publication No. 2010-081609, a technology is thought to be applied, for example, a technology as disclosed in “A 1.5MPixel RGBZ CMOS Image Sensor for Simultaneous Color and Range Image Capture”, Solid-State Circuits Conference Digest of Technical Papers (ISSCC), Session 22/Image Sensore/22.7, 2012 IEEE International, February 2012 (hereinafter referred to as “Literature Document 1”). More specifically, a potential barrier for prevention of effects of charges due to near infrared light (that is, for prevention of the charges due to near infrared light from leaking in) is thought to be disposed in detection pixels arranged in the zigzag pattern.
In addition, for example, in U.S. Pat. No. 7,872,234, and “IR/Color Composite Image Sensor with VIPS (Vertically Integrated Photodiode Structure)”, International Image Sensor Workshop (IISW), 2007 (hereinafter referred to as “Literature Document 2”), a solid-state imaging device in which each of the visible light detection pixel and the near infrared light detection pixel are formed in the same silicon substrate while the positions of each group of pixels is changed in the depth direction. More specifically, each of a depletion layer at a deep position which is ion-implanted with high energy, and a depletion layer at a position close to a surface (shallow position) which is ion-implanted with ordinary energy is formed on the same silicon substrate. In U.S. Pat. No. 7,872,234 and Literature Document 2, visible light is detected by a visible light detection pixel in which a depletion layer is formed at a shallow position, and near infrared light is detected by a pixel for near infrared light in which a depletion layer is formed at a deep position. For this reason, in the solid-state imaging device disclosed in U.S. Pat. No. 7,872,234, and Literature Document 2, a color filter affixed to correspond to each visible light detection pixel has a characteristic of transmitting both of visible light and near infrared light. This is because, the visible light detection pixel and the near infrared light detection pixel are formed at the same position, when a pixel region of the solid-state imaging device is seen from a light receiving surface side, each of visible light and near infrared light is detected depending on a difference in a depth direction.
However, although a technology disclosed in each of Japanese Unexamined Patent Application, First Publication No. 2010-081609, to which the technology of Literature Document 1 is applied, U.S. Pat. No. 7,872,234, and Literature Document 2 is a technology which are able to detect visible light and near infrared light by one solid-state imaging device, a solid-state imaging device to which each technology is applied is not able to separate visible light and near infrared light with high accuracy and detect each type of light due to the following problems.
In a solid-state imaging device disclosed in Japanese Unexamined Patent Application, First Publication No. 2010-081609, with the technology of Literature Document 1 being applied, visible light is also incident on a near infrared light detection pixel. In this case, a near infrared light detection pixel has a sensitivity to a wide range of light from visible light to near infrared light. Therefore, the near infrared light detection pixel detects not only the near infrared light but also the visible light (that is, charges due to visible light are mixed with charges due to near infrared light), and not able to detect only near infrared light. Moreover, in an arrangement of pixels of the solid-state imaging device disclosed in Japanese Unexamined Patent Application, First Publication No. 2010-081609, there is no visible light detection pixel at a position at which the near infrared light detection pixel is arranged. Therefore, in an imaging system equipped with the solid-state imaging device disclosed in Japanese Unexamined Patent Application, First Publication No. 2010-081609, the position at which the near infrared light detection pixel is arranged is handled as a defective pixel in processing of generating a visible light image.
In addition, the solid-state imaging device disclosed in U.S. Pat. No. 7,872,234, and Literature Document 2 is configured to separately detect each type of visible light and near infrared light depending on a difference in a depth direction. For this reason, it is not possible to dispose a potential barrier serving to separate visible light and near infrared light, for example, as in the technology disclosed in Literature Document 1, between the visible light detection pixel and the near infrared light detection pixel. Therefore, charges due to near infrared light may leak into the visible light detection pixel. In addition, conversely, charges due to visible light (particularly, charges due to red (R) visible light) may also leak into the near infrared light detection pixel.
For this reason, the solid-state imaging device disclosed in each of Japanese Unexamined Patent Application, First Publication No. 2010-081609, to which the technology of Literature Document 1 is applied, U.S. Pat. No. 7,872,234, and Literature Document 2 are not able to separate and detect visible light and near infrared light with high accuracy unless the solid-state imaging device is used under specific imaging conditions such as sufficiently bright illumination and the like.